Flowable products such as liquid soaps, adhesives, flavourings, health care products, lubricants and a wide variety of other products are frequently packaged in containers from which they may be dispensed by pressure. Typically, the container is resilient, and may be squeezed thus creating a sufficient dispensing pressure. In other cases pressure may be supplied in other ways, and the container may be rigid. Preferably a dispenser nozzle for such a product will permit dispensing of the liquid when the pressure is applied and will immediatley shut off flow as soon as it is discontinued. Ideally, this function should be performed without having to manipulate the dispenser nozzle, and without having to remove or replace a cap.
In a typical case, such dispenser will in fact be incorporated in the cap of the container, and will preferably serve to seal and close the container after it has been initially filled in the factory, until it is sold to the user. In the simplest system the container is simply inverted and squeezed.
In most cases in the past the dispenser nozzle has been relatively inefficient, and after use it was necessary to stand the container on its base "the right way up", to prevent continued flow of liquid.
This allowed air to flow into the container through the dispenser, to replace the liquid lost during dispensing.
Unfortunately it had the undesirable result of drying out the dispenser. This rapidly became clogged with accumulations of dried liquid, and in many cases it became useless.
While it is no doubt possible to construct a relatively complex dispenser valve performing these various functions, it is obvious that in order to achieve any wide degree of acceptance, especially in connection with relatively low cost products, the dispenser must be of low cost, simple construction, such that it does not require complicated assembly or manufacturing steps, and incorporates a minimum number of parts.
In order to avoid the problem of drying out the dispenser it has been proposed to locate the dispenser at the bottom of the container so that it is essentially "upside down".
However, when this is done the dispenser is thus required to operate under the full hydrostatic pressure of the material in the container, and still act as a seal. This particular feature has proved to be unusually difficult to achieve. In connection for example with liquid soaps and cleansers, it is desirable to market such products in special resilient containers which are provided with a suspension attachment by means of which they may be hung in position, such as adjacent to a work place, sink, or in a shower, for example. The product may then be readily used simply by grasping the container upside down and then squeezing the container to eject a small quantity after which the container may be replaced or stored upside down.
The container holding the liquid will remain standing or hanging upside down with the dispenser at the bottom or at a lower region of the container, supporting the entire weight of liquid within the container.
In the past, dispenser caps have been proposed for this particular usage. However, they have been unsatisfactory to the extent that they did not provide a clean shut-off or sealing of the container, after squeezing had been discontinued. A small quantity of the liquid remains suspended as a droplet from the dispenser, or remains in the dispenser outlet. This liquid would then dry out and lead to malfunction of the dispenser. In some cases the dispenser was blocked, and in others it could cause unsightly deposits or drips of the liquid around the location.
A blocked dispenser would require an extra cleaning operation, and products packaged in this way have not found wide acceptance.
Another problem which is not readily apparent is caused by the bottles or containers themselves. These containers are formed of plastic material, typically being manufactured by blow moulding techniques and for reasons of economy, are manufactured to certain strict limitations as to cost. As a result, the bottles or containers exhibit a comparatively significant degree of irregularity, especially in the region of the neck, or other portion to which the dispenser is attached. In the majority of cases, the dispenser is attached to the neck by some form of threaded means, typically a threaded collar, and is thus clamped into engagement with the edge of the neck. The area of the neck to which the cap is attached is not manufactured to any critical degree of tolerance, and the irregularities present at this point cause significant problems in both the sealing of the dispenser and also in its operation.
The dispenser will usually be manufactured of thermoplastic material, by injection moulding or the like, and may appear to function in a satisfactory manner in the laboratory. However, when it is clamped to a relatively irregular shaped bottle top, such a dispenser may be distorted so that it no longer functions in the manner for which it is intended, or may simply make an inadequate seal with the edge of the neck. In either case, leakage will result.
Some dispensers have been proposed which are essentially two, valved passageways, one valve allowing ejection of liquid and the other allowing re-entry of air.
These proposals do not deal satisfactorily with the problem of the liquid residue left in the ejection valve.
The invention therefore has as its broad objective the provision of a self-closing dispenser for use in dispensing flowable materials, e.g., liquids, from a container by means of pressure, such dispenser being capable of dispensing such material from such container when pressure is applied, and instantaneously shutting off flow when pressure is discontinued and allowing air to return through the ejection passage, to remove the residual material.